1. Field of the Invention
A solid state power supply is disclosed which includes a novel short circuit detector. The detector includes circuits responsive to low potentials indicative of a short to shut the power supply off for a brief period. The detector allows the power to be restored after a short time and will again shut it off in case a short is indicated.
2. Description of the Prior Art
The prior art includes power supplies for telephone switching systems and the like which involve the use of solid state devices. A variety of safety devices have been employed in such power supplies to prevent damage to the supplies in the event of a short circuit. These safety devices commonly include electromechanical devices.
An example of such devices in the prior art is disclosed in U.S. Pat. No. 3,743,887 for a "Power Supply for an Electronic PABX" which issued on July 3, 1973 in the names of T. J. Keough and C. J. Kalensky, and is assigned to the same assignee as the present invention. The system referred to in the patent includes electronic sensing devices which are coupled to a current sensitive relay which responds to excessive current flow to close contacts and supply a voltage causing the system to shut down.
In the prior art, involving the use of two or more switching bays in a system, the power supplies have sometimes been inadequately protected by short circuit detectors in each bay. For example, current may flow on a power distribution bus between the bays at excessive levels after one of the power supplies is shut down.